Physics with Polarized Helium 3

3He， 21Ne和129Xe的极化惰性气体样品为我们在原子，核和核子尺度上研究基本相互作用的多方面计划提供了工具。我们从四年前的探索阶段，通过激光光泵浦Rb的自旋交换，首次实现了大量3He的极化，到成功开发了高进动核磁共振频率谱，实现了3He的极化目标。随着技术的发展，我们能够在一小时的测量间隔内以10-7 Hz的精度测量自由进动频率，并且由于相对于首选方向的质量各向异性而对洛伦兹不变性违反设定了新的限制。对Xe129违反电偶极矩（EDM）的时间反转不变性进行了测量。这种测量应该对10-27 e-cm的电火花敏感。我们对光抽运和自旋交换机制的研究，对包括加速器束电离在内的去极化理论和测量的研究，二极管激光阵列的开发以及新光源的探索，使得极化3He作为中子极化和加速器实验目标的实际应用成为可能。我们现在正在麻省理工学院贝茨直线加速器建立一个实验，通过极化3He的极化电子的准弹性散射来测量中子的电形状因子。我们还将展示一个放大目标的可行性，通过SLAC极化3He的极化电子的深度非弹性散射来测量中子的自旋相关结构函数，目的是尽快进行测量。

Polarized noble gas samples of 3He, 21Ne and 129Xe provide tools for our multifaceted program investigating fundamental interactions at the atomic, nuclear and nucleon scale. We have advanced from the exploratory stage of four years ago, when large quantities of 3He were first polarized by spin exchange with laser optically pumped Rb, to the successful development of high precession NMR frequency spectroscopy and the realization of polarized 3He targets. With the techniques developed, we are able to measure free precession frequencies with a precision of 10-7 Hz in a one hour measurement interval and have set new limits on Lorentz Invariance violation due to Mass Anisotropy with respect to a preferred direction. A measurement of the time reversal invariance violating electric dipole moment (EDM) of Xe129 is underway. This measurement should be sensitive to the EDM at a level of 10-27 e-cm. Our study of the optical pumping and spin exchange mechanisms, theory and measurement of depolarization including ionization by the accelerator beam, the development of diode laser arrays and exploration of new light sources have made possible the practical application of polarized 3He as a target for neutron polarization and accelerator experiments. We are now in the process of building an experiment at the MIT Bates LINAC to measure the electric form factor of the neutron by quasi- elastic scattering of polarized electrons from polarized 3He. We will also demonstrate the feasibility of a scaled up target for a measurement of the neutron's spin dependent structure function by deep inelastic scattering of polarized electrons from polarized 3He at SLAC with the intent of undertaking that measurement as soon as possible.